The present invention generally relates to linear nozzles, i.e., nozzles having a straight, elongated opening, and a tailored gas plume exiting the nozzle for the entrainment and deposition of an atomized liquid material carried in the gas plume.
Linear nozzles can be used for producing spray formed sheet and plate, particularly aluminum sheet and plate, the nozzles depositing molten metal material on a planar surface and substrate. The substrate supports the molten metal until solidification, and acts as a heat sink in the cooling and solidifying process. Linear nozzles have the advantage of making the sheet at desired widths and at production rates that compete with the traditional breakdown and hot rolling of cast ingots. The molten metal is deposited by entrainment in a flow of a gaseous medium directed through the atomizing nozzle and to the substrate.
Linear nozzles can also be used to spray and deposit other atomizable liquid materials, such as coolants, paints, protective coatings or irrigants on the appropriate surfaces.
The velocity profile of the gas flow or plume exiting the nozzle determines the deposit profile independently of the configuration of the supply of liquid medium to the nozzle. In addition, it has been determined that a flat, gas plume will become axisymmetric (circular) downstream of the nozzle due to gas entrainment. Entrainment is more pronounced at the ends or edges of the nozzle so that the gas decelerates at a relatively faster rate at the ends or edges of the plume in comparison to rate of deceleration near and at the plume center. This phenomena is shown in FIG. 1 of the accompanying drawings. The result is a gaussian distribution of the liquid material on the substrate, as shown in FIG. 1.
Prior art efforts to overcome the problem has included the use of a plurality of axisymmetric nozzles scanning over the substrate. Other systems have included multiple nozzles to "fill in" low mass areas of the deposited material, while linear nozzles, using single chamber/single pressure schemes have involved changing the physical geometry of the gas exit of the nozzle for the purpose of controlling the distribution of deposited material. None of these efforts have produced the profile and yield properties needed at required production rates. "Yield" refers to the percent recovery of the liquid as a deposit.